The NIR arm of SHARK: System for coronagraphy with High-order Adaptive optics from R to K bands

Farinato, Jacopo; Baffa, C.; Baruffolo, A.; Bergomi, Maria; Carbonaro, Luca; Carlotti, Alexis; Centrone, Mauro; Codona, Johanan L.; Dima, Marco; Esposito, Simone; Fantinel, D.; Farisato, G.; Gäessler, Wolfgang; Giallongo, E.; Greggio, Davide; Hinz, Philip M.; Lisi, F.; Magrin, Demetrio; Marafatto, Luca; Pedichini, Fernando; Pinna, Enrico; Puglisi, Alfio; Ragazzoni, Roberto; Salasnich, Bernardo; Stangalini, M.; Vérinaud, Christophe; Viotto, Valentina

doi:10.1017/s1473550414000494

“…In case of instrumentation that includes an internal wavefront sensing system, such as SHARK-NIR [14] , able to continuously monitor in real time the image quality, it is in principle possible to correct the NCPA on the DM and counter correct the wavefront on the PWS by AL in closed loop. Typically, NCPA time evolution is small and the correction does not require a high frequency rate.…”

Section: Ncpa Correction With Adaptive Lensmentioning

confidence: 99%

Recovering pyramid WS gain in non-common path aberration correction mode via deformable lens

Magrin¹,

Bonora²,

Quintavalla³

et al. 2017

Proceedings of the Adaptive Optics for Extremely Large Telescopes 5

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It is by now well known that pyramid based wavefront sensors, once in closed loop, have the capability to improve more and more the gain as the reference natural star image size is getting smaller on the pyramid pin. Especially in extreme adaptive optics applications, in order to correct the non-common path aberrations between the scientific and sensing channel, it is common use to inject a certain amount of offset wavefront deformation into the DM(s), departing at the same time the pyramid from the optimal working condition. In this paper we elaborate on the possibility to correct the low order non-common path aberrations at the pyramid wavefront sensor level by means of an adaptive refractive lens placed on the optical path before the pyramid itself, allowing the mitigation of the gain loss.

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“…However, it is worth mentioning here that the SHARK forerunner is designed to minimize NCPA aberrations by simplifying its optical path and picking the beam off very close to the wavefront sensor. 25,27 Further, during the observation, the NCPAs aberrations were mitigated by injecting an offset on the secondary DM of LBT following the procedure described in Ref. 31.…”

Section: Data Setmentioning

confidence: 99%

“…To complement these studies, in this work, we exploit new data acquired by the System for Coronagraphy with High-order Adaptive Optics from R to K bands (SHARK) forerunner experiment [25][26][27][28] at a very high cadence (1 ms) and visible wavelengths. These data allow us to study the behavior of residual AO speckles down to very short timescales and assess the atmospheric clearance time with very high accuracy.…”

Section: Introductionmentioning

confidence: 99%

Speckle statistics in adaptive optics images at visible wavelengths

Stangalini

¹

,

Pedichini

²

,

Ambrosino

³

et al. 2016

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Abstract. Residual speckles in adaptive optics (AO) images represent a well-known limitation on the achievement of the contrast needed for faint source detection. Speckles in AO imagery can be the result of either residual atmospheric aberrations, not corrected by the AO, or slowly evolving aberrations induced by the optical system. We take advantage of the high temporal cadence (1 ms) of the data acquired by the System for Coronagraphy with High-order Adaptive Optics from R to K bands-VIS forerunner experiment at the Large Binocular Telescope to characterize the AO residual speckles at visible wavelengths. An accurate knowledge of the speckle pattern and its dynamics is of paramount importance for the application of methods aimed at their mitigation. By means of both an automatic identification software and information theory, we study the main statistical properties of AO residuals and their dynamics. We therefore provide a speckle characterization that can be incorporated into numerical simulations to increase their realism and to optimize the performances of both real-time and postprocessing techniques aimed at the reduction of the speckle noise.

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“…Recently other authors 9 have investigated the speckle lifetime in the H-band, by exploiting a 1.6 Hz cadence set of extreme AO (ExAO) images. In order to complement these studies, in this work we exploit new data acquired by the SHARK forerunner experiment 25,26,27,28 at very high cadence (1 ms), and visible wavelengths. This data allows us to study the behavior of residual AO speckles down to very short timescales, and assess the atmospheric clearance time with very high accuracy.…”

Section: Introductionmentioning

confidence: 99%

Speckle statistics in adaptive optics images at visible wavelengths

Stangalini

¹

,

Pedichini

²

,

Pinna

³

et al. 2017

J. Astron. Telesc. Instrum. Syst

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Abstract. Residual speckles in adaptive optics (AO) images represent a well-known limitation on the achievement of the contrast needed for faint source detection. Speckles in AO imagery can be the result of either residual atmospheric aberrations, not corrected by the AO, or slowly evolving aberrations induced by the optical system. We take advantage of the high temporal cadence (1 ms) of the data acquired by the System for Coronagraphy with High-order Adaptive Optics from R to K bands-VIS forerunner experiment at the Large Binocular Telescope to characterize the AO residual speckles at visible wavelengths. An accurate knowledge of the speckle pattern and its dynamics is of paramount importance for the application of methods aimed at their mitigation. By means of both an automatic identification software and information theory, we study the main statistical properties of AO residuals and their dynamics. We therefore provide a speckle characterization that can be incorporated into numerical simulations to increase their realism and to optimize the performances of both real-time and postprocessing techniques aimed at the reduction of the speckle noise.

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The NIR arm of SHARK: System for coronagraphy with High-order Adaptive optics from R to K bands

Cited by 21 publications

References 36 publications

Recovering pyramid WS gain in non-common path aberration correction mode via deformable lens

Recovering pyramid WS gain in non-common path aberration correction mode via deformable lens

Speckle statistics in adaptive optics images at visible wavelengths

Speckle statistics in adaptive optics images at visible wavelengths

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